Please help - With explanation

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Please help - With explanation

Postby Sudoku123456789 » Sat Sep 16, 2017 3:25 pm

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Please explane solution


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Last edited by Sudoku123456789 on Sun Sep 17, 2017 12:40 pm, edited 1 time in total.
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Need help - got stuck - explane solution please

Postby Sudoku123456789 » Sun Sep 17, 2017 12:24 pm

Tried many techniques. Explain solution please.
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Re: Please help - With explanation

Postby Sudoku123456789 » Sun Sep 17, 2017 12:39 pm

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Re: Please help - With explanation

Postby JC Van Hay » Mon Sep 18, 2017 10:53 am

In spite of the lack of marking of the bilocals in the possibibity matrix, the bivalues fortunately lead to a simple solution. To wit, the 2 solutions of R1 exclude 5r5c4; stte
Code: Select all
+--------------------+----------------------+-----------------+
| 3     7     (89)   | 4       5      1     | 2     6(9)  68  |
| 4     28    2589   | 7       389    6     | 589   1     38  |
| 5689  68    1      | 9(23)   389    28    | 4     35    7   |
+--------------------+----------------------+-----------------+
| 58    238   2358   | 1       7      (258) | 6     4     9   |
| 7     46    456    | -5(36)  34(6)  9     | 18    2     18  |
| 1     9     246(8) | (26)    4(68)  24(8) | 3     7     5   |
+--------------------+----------------------+-----------------+
| 689   1468  4689   | 569     2      457   | 1579  35    136 |
| 2     5     7      | 8       19(6)  3     | 19    (69)  4   |
| 69    1346  3469   | 569     1469   457   | 1579  8     2   |
+--------------------+----------------------+-----------------+
8r1c3 -> 8r6c56; 5r4c6 or 2r4c6, 2r3c4, 3r5c4 => -5r5c4
or
9r1c3 -> 9r8c8, 6r8c5, hidden triple (236)r356c4 => -5r5c4

Other ways to proof -5r5c4 :

1. Forbidding matrix :
Code: Select all
 5r5c4
|3r5c4 3r3c4      |
|      2r3c4 2r6c4|
|6r5c4       6r6c4|6r56c5
                   6r8c5  6r8c8
                          9r8c8 9r1c8
                                9r1c3 8r1c3
                                      8r6c3 8r6c56
 5r4c6       2r4c6                          8r4c6  : IOW 5r5c4 -> r4c6 is empty
2. This wysiwyg forbidding matrix can be written in Eureka notation as a Kraken Cell (258)r4c6 :
HT(236)r356c4=6r56c5-6r8c5=(6-9)r8c8=9r1c8-(9=8)r1c3-8r6c3=8r6c56-8r4c6=*Wing[(5=*2)r4c6-2r6c4=(2-3)r3c4=3r5c4] -> derived SIS/constraint {3r5c4, 6r5c4, 5r4c6} :=> -{5r5c4}; stte

3. ...
JC Van Hay
 
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Re: Please help - With explanation

Postby Sudoku123456789 » Mon Sep 18, 2017 1:03 pm

Sorry, i'm very new to this.

Are there any guides available to this terminology?

Thanks in advance for the solution.
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Re: Please help - With explanation

Postby Sudoku123456789 » Mon Sep 18, 2017 2:26 pm

Thank you JC for the many help. I unfortunately have 1 last question.

Which technique did you use to validate -5r5c4? Is this the chaining technique?
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Re: Please help - With explanation

Postby JC Van Hay » Mon Sep 18, 2017 4:55 pm

http://www.sudokuwiki.org/Cell_Forcing_Chains applied twice : first from (89)r1c3, then from (25)r4c6 for one of the chain.
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